How would a Twelver Shia prove Imam Mahdi's long life to an Atheist?

A Twelver Shia might attempt to prove the long life of Imam Mahdi to an atheist by presenting a combination of Islamic teachings, historical context, and logical reasoning. One key point in their argument could involve the concept of occultation, which is the belief that Imam Mahdi is currently in a state of hiddenness but will return when the time is right.

In the hadith literature, it is noted that the Mahdi must experience occultation. A narration in Al-Kafi states, He fears, and he pointed to his stomach, meaning the awaited one, the one about whom people doubt his birth; some say it was a pregnancy, some say his father died leaving no offspring, and some say he was born two years before his father died Al-Kafi 4:489Shia. This suggests that his birth and life have been subjects of speculation and belief over time.

Additionally, Shia belief emphasizes that Imam Mahdi's long life serves a divine purpose. They argue that his extended existence is necessary for him to fulfill his role in restoring justice and equity in the world, as prophesied in Islamic texts. This concept can be appealing even to those skeptical of religious claims, as it aligns with a narrative of hope and justice that many people can relate to.

Furthermore, proponents may argue that the belief in the Mahdi’s long life is supported by historical precedents of other religious figures whose lives were extended for significant missions, thus drawing parallels that might resonate with an atheist's understanding of history and purpose.